More than half of Conservative parliamentary party decline to support PM on issue at heart of his modernising agenda

Parliament took a historic step towards embracing full equality for gay people when MPs voted on Tuesday overwhelmingly in favour of equal marriage at the end of a charged Commons debate that exposed the deep rift over David Cameron’s modernising agenda at the heart of the Conservative party.

The 225-vote majority, greeted with rare applause in the public gallery, was marred for the prime minister, who suffered a humiliating rebuff when more than half of the parliamentary Tory party declined to support the government on an issue he has personally invested in.

Owen Paterson, the environment secretary, led an unofficial rebellion by an estimated 136 Tory MPs in rejecting Cameron’s plea. The opponents – including two tellers – included Adam Afriyie, the MP for Windsor, who has been running a Tory leadership campaign.

About 40 Conservatives, including the attorney general, Dominic Grieve, either formally abstained or did not vote in the second reading of the bill, which was subject to a free vote in which MPs were entitled to follow their consciences.

The result meant the prime minister, who won the support of an estimated 127 Tory MPs, including one teller, failed to win more than half of his 303 MPs.

But the bill is likely to reach the statute book, assuming it has a safe passage through the Lords, after support from Labour and Liberal Democrat MPs ensured it got an overwhelming second reading.

Desmond Swayne, a Tory whip who used to serve as the prime minister’s parliamentary private secretary, proudly announced to the chamber that 400 MPs had voted in favour of the bill, with 175 voting against.

The prime minister welcomed the vote. He tweeted: “Strong views exist on both sides but I believe MPs voting for gay people being able to marry too, is a step forward for our country.”

Nick Clegg said: “I genuinely believe that we will look back on today as a landmark for equality in Britain … No matter who you are and who you love, we are all equal. Marriage is about love and commitment, and it should no longer be denied to people just because they are gay.”

The Roman Catholic church made clear that it would use the strong objections to the bill voiced by MPs across the house to maintain its campaign against same-sex marriage. The Most Reverend Peter Smith, Archbishop of Southwark, said: “The Catholic Church continues to support marriage understood by society for centuries as the significant and unique lifelong commitment between a man and a woman for their mutual well-being and open to the procreation and education of children. Marriage is rooted in the complementarity of man and woman.

“For these reasons the Church opposes the government’s Bill to re-define marriage. Despite claims by supporters of the Bill that the central issue is one of equality, the Bill actually seeks to re-define marriage and will have consequences for society at large.

“It became clear during today’s debate in the House of Commons that the government has not thought through a number of profound problems in the bill raised by members of parliament during the debate. It will be extremely important that the many concerns we and others have expressed will be fully and carefully considered during the next stages of the bill’s passage through parliament.”

One prominent Tory opponent of the bill endorsed the church’s view. The MP said: “This legislation is asking for trouble. The lawyers will be rubbing their hands.”

Colin Hart, campaign director of the anti-equal marriage group Coalition for Marriage, said: “The scale of the opposition against the government’s profoundly undemocratic plans is astonishing, and sends a clear message to the prime minister that he faces a lengthy and damaging battle to redefine marriage.

“Just a few months ago, if we had predicted this result, no one would have believed us, but our clear and simple message that these proposals are undemocratic and will lead to all sorts of unintended consequences has struck a chord with ordinary voters and now scores of MPs.

“We have consistently warned the legislation contains no safeguards for those who work in the public sector. Top lawyers, with a track record of winning against the government, have said the quadruple lock is not sustainable and instead of trying to answer these questions the PM remains hell bent on ramming this bill through parliament in a dangerously short period of time.

“Mr Cameron hopes that this matter is now settled. He is wrong. His attempts to distract those in his own party and the wider country from the fall out will fail. More importantly this is not the end of the fight against these ill-thought through and divisive plans. There are more votes in the Commons, more speeches, potentially dozens of amendments and then the bill will go to the Lords where the voting arithmetic is very different.”

Ben Summerskill, the chief executive of Stonewall, said: “As the last piece of the legislative jigsaw providing equality for gay people in Britain, this is a truly historic step forward.

“We’re absolutely delighted that MPs have demonstrated so overwhelmingly that they’re in touch with the 21st century. We anticipate, as always, a tough battle in the House of Lords. Happily, the size of the commons majority seen tonight – much larger than for most normal government business – will make it very difficult for peers to suggest that the bill should be rejected.

“Most people in Britain support equal marriage and will be delighted that we’re now a step closer to it. We’re grateful to the thousands of Stonewall supporters, many of them straight, who played a big part by contacting their MPs in support.”

The vote prompted angry recriminations among Tory supporters of reform who criticised Cameron for failing to offer wholehearted support for the reform.

A promised statement by the prime minister was hurriedly recorded for television cameras late on Tuesday afternoon four hours after Maria Miller, the equalities minister, had opened the debate.

One reformer said: “The prime minister couldn’t even be bothered to turn up in the chamber. That is so fucking rude. This will have a corrosive effect. The politics around this have been so bad.”

The criticism of the prime minister was voiced after MPs from all the main parties lined up on opposing sides. Margot James, Tory MP for Stourbridge, warned her colleagues that the Conservative party would suffer the same fate as the Republicans in the US unless it wholeheartedly embraced social reform.

But Sir Roger Gale, the veteran Tory MP for Thanet North, lambasted the government. “Marriage is the union between a man and a woman – has been historically, remains so. It is Alice in Wonderland territory, Orwellian almost, for any government of any political persuasion to seek to come along and try to rewrite the political lexicon.”

Tory modernisers were horrified by the speeches by opponents of reform. One minister said: “Yes we can confidently say that the Tory party is divided – and divided right down the middle on this one. And with the help of four or five speeches we have been taken back more than 50 years to the horrors of the 1950s.”

Philip Hammond, the defence secretary who opposes equal marriage, did not vote because he is away on official business. His ministerial colleague Andrew Robathan, one of Cameron’s original supporters in the 2005 Tory leadership contest, voted against the bill. He was joined by Mike Penning, the Northern Ireland minister, and by Robert Goodwill, a senior whip.

Clegg failed to win the support of four Lib Dem MPs. They were Sir Alan Beith, John Pugh, Gordon Birtwistle and the former children’s minister Sarah Teather.

Ed Miliband failed to win the support of 22 Labour MPs who voted against the bill. They included the shadow justice minister Robert Flello.